Sandra Costanzo

NEAR-FIELD TO FAR-FIELD TRANSFORMATION WITH PLANAR SPIRAL SCANNING

A transformation procedure directly computing the antenna far-field pattern from near-field samples acquired on a planar spiral is proposed in this paper. The convolution property of the radiation integral is exploited to efficiently perform the evaluation by taking advantages of the Fast Fourier Transform, without the need of any intermediate interpolation process. Validations on circular arrays of elementary dipoles are presented to show the effectiveness of the method.

Hybrid Array Antenna for Broadband Millimeter-Wave Applications

A hybrid array configuration suitable for wideband millimeter-wave applications is presented in this work. The proposed structure is based on the use of circular waveguide elements electromagnetically coupled trough circular apertures to a stripline distribution network. The adopted excitation mechanism avoids the use of transition components generally reducing the overall antenna efficiency. Simulated and measured results on a Ka-band prototype are discussed to prove the wideband radiation behavior.

An integrated probe for phaseless near-field measurements

A novel approach for phaseless near-field measurements is presented. The squared amplitudes received by two co-planar probes simultaneously scanning a near-field planar surface are used to retrieve the near-field phase information and subsequently to perform the near-field/far-field transformation. The approach is advantageous with respect to both microwave holography and existing phase retrieval techniques, since it does not require any increase in the cost of the measurement facility or in the scan time, so conventional low-cost near-field equipments can be used. The effectiveness of the technique is shown by reporting experimental validations on measurements of a microstrip patch antenna for SAR applications.

Software defined radar: synchronization issues and practical implementation

The present work is focused on Software Defined Radar - (SDR) paradigm, which gives a more versatile solution when compared to classical radar systems. Thanks to this new system model, most of the fundamental operations, such as signal generation, filtering, up and down conversion, are easily implemented via software. The objective of this paper is to show the main issues related to the design of an effective Software Defined Radar device. Specifically, we will discuss and face the synchronization issues existing between a received and a transmitted signal when an open source hardware, namely the Universal Software Radio Peripheral (USRP), is considered.

Support Vector Regression Machines to Evaluate Resonant Frequency of Elliptic Substrate Integrate Waveguide Resonators

In this paper an efficient technique for the determination of the resonances of elliptic Substrate Integrated Waveguide (SIW) resonators is presented. The method is based on the implementation of Support Vector Regression Machines trained using a fast algorithm for the computation of the resonant frequencies of SIW structures. Results for resonators with a wide range of parameters will be presented. A comparison with results obtained with Multi Layer Perceptron Artificial Neural Network and with full wave simulations will show the effectiveness of the proposed approach.

Beam-Scanning Reflectarray Based on a Single Varactor-Tuned Element

A single varactor-tuned element is investigated as effective solution for the realization of reconfigurable reflectarray antennas. The proposed configuration is successfully implemented for the design of an X-band reflectarray prototype of 3×15 radiators. A dedicated electronic control board is designed as an integral part of the antenna. Good performances in terms of beam-scanning capabilities are obtained from measurements.

Compact U-slotted antenna for broadband radar applications

The original U-shaped patch antenna is properly modified in this work to provide a compact and broadband antenna configuration with reduced cross-polar effects, well suitable for modern radar applications. The proposed antenna layout is applied to design, realize, and test two different prototypes working at P-band and C-band, typically adopted for ground-penetrating radar. The experimental results successfully demonstrate a large operating bandwidth between 15% and 20%, a significant reduction of size (about half of the standard configuration), and a low cross-polarization level within the operating frequency range.

Compact Slotted Antenna for Wideband Radar Applications

A new type of slotted microstrip antenna, suitable for wideband radar applications, is proposed in this work. The standard U-slot shape, usually adopted to enlarge the operating bandwidth of a microstrip patch, is properly modified to reduce the undesired cross-polar effects, while providing also a significant size reduction. Validations on X-band and P-band, useful for radar applications, are successfully discussed. In particular, a P-band prototype has been manufactured and tested, while the numerical simulation results of an X-band antenna, performing a 45% bandwidth, are successfully reported.

Software-Defined Radar System for Landslides Monitoring

An integrated system for landslides early warning, based on a flexible network architecture and including different sensors, is described to monitoring landslides evolution in critical scenarios. Particular focus is devoted on the experimental assessment of an L-band Software Defined Radar sensor, specifically designed for the application, by discussing the measurement results obtained on a real landslide scenario located on the A3 highway in Calabria (Italy). In particular, a mathematical estimator useful for the proper detection of landslide movements is defined and applied to the measured range profiles, thus demonstrating the usefulness of the proposed radar monitoring approach.

Compact MUSA: Modified U-slot patch antennas with reduced cross-polarization.

A modified U-slot patch antenna (MUSA) is proposed in this article to provide a compact radiating structure with reduced cross-polarization effects when compared with the standard U-slot geometry while assuring an adequate bandwidth percentage between 15 and 20. A synthesis procedure is outlined for the proposed antenna configuration, and it is assessed both numerically and experimentally at different frequencies between 1 and 10 GHz for different dielectric substrates.